1. Field of Invention
The invention relates to apparatus for the remote control of transfer operations in which a material is transferred from a supply tank into a tank to be filled and more particularly for a device for the failsafe manual remote control of a valve and pump used in the filling operation.
2. Description of the Prior Art
In a known device for the remote control of tanking operations at airports, a manual device such as a hand rubber ball, button or lever switch, is connected by a hose or cable to the control device of the tanker and is maintained in an activated state by the operator as long as the filling operation is to continue. If the manual device is released, the control device closes the filling valve. Such a device is very inconvenient for the operator, as it can cause cramps in the operator's hand. In practice, the operator is not precluded from blocking the manual device. Thus, a hand rubber ball can be wedged and pressed down under a wheel of the tanker thereby defeating its safety function. However, in certain instances, such as refueling of aircraft remote manual control is absolutely essential because it is not assured in practice that the amount of fuel to be taken on as requested the flight personnel is accurate or is consistent with the capacity of the tank. Incorrect setting of the desired amounts at the control device is another source of error. Furthermore, the tanker hose can also become defective or other problems can occur.
Similar problems occur generally in the transfer of dangerous liquids or other materials such powders or granular materials. The danger may be due to flammability, poisonous nature or the like of these materials. It may also involve expensive material which must not be spilled or generally operations executed by robots which are to be controlled effectively by hand.